Git GUI vs interactive post-commit hooks

Hi, list!

$ git --version git version 1.5.5.1

I have a post-commit hook which does backups for me:

  username=agladysh
  for name in `git branch | cut -b3-`
  do
    remote=$username-$name
    echo pushing $name as $remote
    git push backup +$name:refs/heads/$remote
  done

The backup repo is behind ssh. Recently I have put password on my ssh key and post-commit hook ask me for password once for each branch. This makes unhappy commit process from Git GUI -- after I shut it down, there are multiple ssh key password prompts in the shell from where I launched it, and it does not display any input I enter.

Any advice? I do want to input password for my key each time I use it.

Thanks in advance, Alexander.